The Puquios of Las Trancas: A GIS-Based Analysis of Irrigation, Settlement, Political Development, and Colonial Interaction on Peru's South Coast (AD 1-1450)

Abstract

This thesis takes a geographic information system (GIS) based approach in landscape archeology to explore how different groups interacted with a network of underground aqueducts known as the puquios and the arable land they serve, from the beginning of the Early Intermediate period (EIP) (AD 1 – 650) through the end of the Late Intermediate Period (LIP) (AD 1000 – 1450) in the southernmost valley of the Nasca drainage, called Las Trancas. The project utilizes a combination of diverse geospatial and geostatistical methodological procedures to reconstruct the historical expression of irrigation infrastructure and its spatial relationship to ancient settlements in the valley, including georeferencing historical aerial photographs and satellite imagery, viewshed modeling, least cost path (LCP) analysis, Principle Component Analysis (PCA) of multispectral satellite datasets, and unsupervised machine learning (ML) classification. The processing of multispectral indices enabled the visualization and mapping of a previously undocumented puquio (LTV11), along with auxiliary branches of two others (puquios La Joya and Pampón), which had been reported, but unobserved prior to this work. The results from statistical analyses of viewshed and LCP metrics find that the first puquios in the Las Trancas Valley were likely constructed sometime prior to the 4th century, and a shift from the decentralized irrigation-based social organization shortly after consolidated control of agricultural resources, leading to a more territorial settlement strategy. These settlements were abandoned during the Middle Horizon (AD 500 – 750), as Wari expanded the valley’s irrigation infrastructure and absorbed the puquios into imperial economic networks. As central authority dissolved following the collapse of Wari, irrigation networks remained central to local autonomy and competition during the LIP. These patterns support broader theories of hydraulic management and circumscription, positioning the puquios as enduring instruments of technological innovation, political authority, and adaptive resilience.Anthropolog